Form I-MAPSIII&IV, Page 56
WARNING
The operating valve is the prime safety shutoff. All gas supply
lines must be free of dirt or scale before connecting the unit to
ensure positive closure.
9. Optional
Equipment
(cont'd)
WARNING
All components of a gas supply system must be leak tested prior to placing equipment in
service. NEVER TEST FOR LEAKS WITH AN OPEN FLAME. Failure to comply could result
in personal injury, property damage or death.
Sizing Gas Supply
Lines
Capacity of Piping
Cubic Feet per Hour based on 0.3" w.c. Pressure Drop
Specic Gravity for Natural Gas -- 0.6 (Natural Gas -- 1000 BTU/Cubic Ft)
Specic Gravity for Propane Gas -- 1.6 (Propane Gas -- 2550 BTU/Cubic Ft)
Length Diameter of Pipe
of 1/2" 3/4" 1" 1-1/4" 1-1/2" 2"
Pipe Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane Natural Propane
20' 92 56 190 116 350 214 730 445 1100 671 2100 1281
30' 73 45 152 93 285 174 590 360 890 543 1650 1007
40' 63 38 130 79 245 149 500 305 760 464 1450 885
50' 56 34 115 70 215 131 440 268 670 409 1270 775
60' 50 31 105 64 195 119 400 244 610 372 1105 674
70' 46 28 96 59 180 110 370 226 560 342 1050 641
80' 43 26 90 55 170 104 350 214 530 323 990 604
90' 40 24 84 51 160 98 320 195 490 299 930 567
100' 38 23 79 48 150 92 305 186 460 281 870 531
125' 34 21 72 44 130 79 275 168 410 250 780 476
150' 31 19 64 39 120 73 250 153 380 232 710 433
175' 28 17 59 36 110 67 225 137 350 214 650 397
200' 26 16 55 34 100 61 210 128 320 195 610 372
Note: When sizing supply lines, consider possibilities of future expansion and increased requirements.
Refer to National Fuel Gas Code for additional information on line sizing.
Cabinet
Size
Heat Section
Gas Connection
Natural Gas Propane
A 100, 150, 200 1/2” 1/2”
B 250, 300 3/4” 3/4”
C 400, 500, 600, 700 1” --
D
500, 600, 700, 800,
100, 1200, 1400,
1600
1” --
Manual
Valve
Drip Leg
Union
Reduce supply line.
Gas connection
is 1” npt.
FIGURE 37 - Gas Connection
(D Cabinet illustrated)
Supply Pressures
Before attempting to measure valve outlet and manifold gas pressure, the inlet supply
pressure must be within the specied range both when the heater is in operation and
on standby. Incorrect inlet pressure could cause excessive valve outlet gas pressure
immediately or at some future time.
Natural gas inlet supply pressure for all gas control systems must be a minimum of 6.0"
w.c. Maximum natural gas supply pressure is 14" w.c.
Furnaces for natural gas are oriced for operating with gas having a heating value of
1000 (±50) BTU per cubic ft. If the gas at the installation does not meet this specica-
tion, consult the factory for proper orice.
Pipe joint compounds (pipe dope) shall be resistant to the action of liqueed petroleum
gas or any other chemical constituents of the gas being supplied.
9.2 Gas Heat -
Models RDCB,
RDDB, RDCC,
RDDC (cont'd)
9.2.1.2 Gas Piping and Pressures (cont'd)
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